He opposes the Common Core education standards, describing them as "anti-American propaganda, revisionist history that ignores the faith of our Founders and data-tracking of students from kindergarten on."

He has proposed a flat tax of 17 percent and wants to eliminate estate and gift taxes as well as investment taxes.

Paul opposes gay marriage. "States will end up making the decisions on these things," the U.S. senator from Kentucky said during an interview on CNN. "I think that there's a religious connotation to marriage. I believe in the traditional religious connotation to this. But I also believe people ought to be treated fairly under the law. ...

"You probably could have both," added Paul, known for his libertarian views. "You could have both traditional marriage, which I believe in, and then you could also have the neutrality of the law that allows people to have contracts with another."

He says he supports free trade expansion but voted against giving President Barack Obama fast-track authority to get the Trans-Pacific Partnership through Congress. "I still might vote for the trade agreement, but I hate giving up power. We give up so much power from Congress to the presidency, and with them being so secretive on the treaty, it just concerns me what's in the treaty," Paul said in May.